Tube adapter



May 11 1926.

R. W. CAMFIELD TUBE ADAPTER Filed March 2, 1925 FIE.

Patented May 11, 1926.

UNITED STATES PATE NT oFFici-..

RUSSELL W. CAMFIELD, F BERKELEY, CALIFORNIA, ASSIGNOR TO E. T. CUNNING- HAM, 0F SAN FRANCISCO, CALIFORNIA.

TUBE ADAPTER.

Application nid Maren 2, 1923. serial 119-622,282.

rI`his invention relates to an'adapter for a vacuum tube, such as is used in connection with radio signaling. At the present time there are several sizes of vacuum tubes or thermionic devices on the market, and each type has been used extensively. In order'to change from one kind of tube to the other in the same system, the tube socket must also be changed so as to cooperate properly Withth/e,

contacts on the device which it is desired to use. One manner in' which the change may be readily accomplished from one kind of socket to anotherislby the provision of an adapter that is arranged to fit removably inside of a socket. With the adapter removed, the tube having the `larger base may be directly accommodated within the socket. To takel care of the tube havingthe smaller base, the adapter is first inserted int-o .the

20. socket, and then the tube is placed into the adapter. Of course thel ada ter carries contacts that serve to connect t e tube contacts with those of the socket.

It is one of the objects of my invention to provide an adapter of this sort that is sim ple and| inexpensive to manufacture.

It is another ob'ect of my invention to provide a spring-pressed contacting device, adapted for use in connection with thermiloiiic tubes, in Vwhich the parts are few and rugged, and in 'which' there is a certainty that proper electrical connections may be maintained even after continued and prolonged use.

My invention possesses other advantageous features, some of which, with the foregoing,

will be set vforth at length in the following description, where I shall outline in fullthat form of the invention which I have selected for illustration in the drawings accompanying and forming partof the present specification. Although I-have shown in the drawings bfut one embodiment of my invention, I do'not desire to be limited thereto, since the invention as expressed in the claiins may be embodied in other forms also.v v

Referring to the drawings: Figure 1 is a view of a tube, fitting into an adapter embodying my invention, which .adapter is shown as inserted into a socket; the adapter `and socket being mainly in section; Y

Fig. 2 is an enlarged sectional view of the top portion of one of the contacts used in the adapter shown in Fig. 1;

Fig. 3'is an elevation of the lower part of a vacuum tube, showing the base'which is capable of cooperating with an adapter embodying my invention Fig. 4 is an elevation of the adapter; and

Fig. 5 is a bottom plan view ofthe adapter shown in Fig. 4. 4 The tube socket 11 in the present 'instance is shown. as madeof insulation material and as comprising ahollovv portion 12, in the bottom 13 of which there arek apertures 14. Ihcse apertures are provided to permit the' fpassager of contact posts or p-rcngs associat there is produced a rubbing contact between these at'springs 17 and the contact'posts whenever the tube is so iinserted Within the c socket as to project the contact posts through the apertures l In order to prevent any improper connection from the tube elements to the external circuits, it is customary in this type of apparatus to provide for at least one cont-act post or prong of different size or shape from the others, and also preferably spaced` irregularly with respect to the center of the socket and the remaining posts. lThus there is ius't one relative position of the socket andf tube which will'permit the insertion of the'contact posts in the apertures 14. Furthermore a central aperture 19 in the portion 13 may be` provided for accommodating a central projection. Although a special form f of socket 11 has been described, it is of course to be understood that many of the features of my invention may be utilized With substantially any other type o'f socket.

Theadapter 20, shown most clearly in Figs. 4 and 5, is provided with a plurality of contact posts or prongs 21, 22, 23 and 24, which correspond to those of the tube for which the socket llwas originally designed. It is to be noted that prong 24 is larger in diameter than the others, and that it is unl ',.farthei vfrom the central boss 25. vThese resilient manner, so that they may cooperate properly with the contacts 29 located on the base 30 of a tube 3l. The studs 28 have each a shank portion 32, as' shown most clearly in Fig. 2, which projects into the enlarged hollow portion 27 of the contact post. A shoulder 33 is formed at the bottom of the longitudinal aperture 34 so as to anchor the last turn of the spring 35 in this'aperture. The spring is utilized to support the stud 28 and to nrge it resiliently against the tube contactsl 29.` For thispurpose, `it surrounds the shank 32 and is anchored to the shank by the aid of an annular projection or flange 36 formed on the shank. y

The manner of assembling the contact and its spring within the post 21, 22, 23 or24 is extremely simple. The spring 35 isl pressed over the projection 36 so that at least one turn of the springVK is held between this projection and the head 28. Then the bottom turn of thevspring is expanded so that in its free condition it will have a -diameter appreciably larger than that of the other turns.

This turn is then temporarily compressed to a smaller diameter so that it may enter aperture 34, and it is placed into the aperture and urged toward the bottom thereof. As soon as the last turn slipsA past the shoulder 33, it expands to its free size, and

snaps underneath the shoulder 33. The last' turn is thus securelyy anchored in the enlarged space 37 at the bottom of thek aperture 34. This type ot' vContact; may also be used advantageously in connection withany form of tube socket, and is not limited in use to an adapter. Y

In the present instance, the adapter 20 is shown as arranged to accommodate a tube 31 which has a radial pin 38 projecting from its base 30. This pin may enter the bayonet slot 39 formed at the top of the hollow cylindrical portion 40 of the adapter 20.

This portion may be formed integral with the base 26, but in the present instance I have shown it as made of metal and embedded within the base. The external diameter of this portion 40 must of course be slightly less than the internal diameter of socket 11.

It is evident that the adapter may, by appropriate change in design, serve to provide a connection socket for substantially any type of tube that is smaller than the socket within which the adapter is accommodated. Furthermore, the resiliently supported contact studs 28-are reliable in service; all/11ability of mis-alinementor of loosening of the contacts is obviated by the scheme'fof anchoring described..

I claim:

l. In an adapter for a thermionic tube, an insulating base, a contact post having an aperture in one end held by said base so that the post projects therethrough, said aperture having an enlargement near the bottom, forming a shoulder, a coiled spring disposed in the aperture and having a portion of its turns of larger diameter than the remainder for anchoring the spring on the shoulder at one end, and a contact stud attached to the opposite end of the spring.

2. A Contact post having an aperture, said aperture being enlarged at its bottom so as to form a shoulder, a coiledspring in said aperture having a portion'of itsl turns otlarger diameter than the remainder for anchoring the spring on the shoulder at one end, and a contact stud attached to the opposite end of the spring.

3. A contact post having an aperture, said aperture being enlarged at its bottom so as to form a shoulder, a coiled spring in said aperture'having a portion of its turns of larger diameter than the remainder for anchoring the spring on the shoulder, and a contact stud having a shank encircled by the spring, said stud being provided with an annular projection for anchoring it to the spring.

In testimony whereof, I `have hereunto setmy hand.

RUSSELLW'. CAMFIELD. 

